And I honestly couldn't find anything else...most armor I could find was normal...

How can I make armor like that? Where it looks like one solid piece, yet I still have the ability to (fairly) easily take it on and off? And buckles or straps would show or would be impossible to adjust if put on the inside.

There's really no way to make a fitted bracer seamless. You can do them so they're large enough to slide your hand through but they won't be tight enough on your forearms.
The best way I've seen is to create the bracer out of one piece (or two pieces with one seam smoothed away), and then have an "invisible" join by means of small rare earth magnets.

I'm trying to find a tutorial, the 501st use the method all the time to make seamless armour, and I can't bloody find it.
So here's my crappy ASCII interpretation.

========||=v======
...........[____^]

WHOA HOW AWESOME AM I, right?
So you've got your actual bracer that butts together, and then a strip that sits underneath them, glued to one side, and magneted to the other. And obviously your "v" magnet wouldn't be visible.

This means that you can carefully stretch your bracers out and slide your hand through them and reclose them to as fine a gap as you can manage. Normally all you really need is an extra CM allowance to get your hand through.

If I've completely confused the crap out of you, I'll go find one of our pieces of armour that we've used this method on, and show you.

The only way I can think of to make a truly seamless bracer would be to cast it out of liquid rubber. It's a lot of work. You'd probably have to use a lathe to shape the original seamless bracer, then create a negative mold of that, then cast duplicates with silicone rubber. If you include the metallic powder additive, that will give the rubber bracer a truly metallic look. A rubber bracer would stretch enough to get your hand through the narrow wrist opening. Or you can use one of the semi-rigid urethane plastics if you want stiff bracers. The plastic should flex enough to allow you to put the bracers on. You'd probably sweat a bit under the rubber/plastic, but *shrug* It's the only way I can think of to make it truly seamless.
I think it'd just be easier to make regular seamed bracers and just be mindful to turn the seam away from the camera whenever you're having photos taken.

If you could make a cast of your forearm's shape, and had access to vacuum forming, you could (in theory) use a pliable material to make a seamless gauntlet. There is of course a limit to each material's stretch when being vacuum formed.

The other method I can think of is making a bracer that is purposely oversized along its cross-section. You can use any method you like for creating the gauntlet, and once it is over your arm using a fabric or foam that you can slip inside to make it snug against your flesh.

This has always bugged me, even as a kid. I used to imagine that these heros would put the bracers on as kids and then just leave them on until they grew into them, at which point, they'd never be able to take them off again.

Naturally, such things don't exist in the real world of armor. It comes from artists either not wanting to draw that level of detail, or just being ignorant about how real world armor needs to function.

I can't recall exactly which characters they were, but I've seen a few "making of" featurettes that demonstrated Hollywood-grade props where they cast it from either foam latex (which is a huge pain to work with) or flexible polyurethane foam. The process is pretty much just as Astillar described. Silicone rubber would be a nice alternative in that various formulations of it have a higher tear strength; also nice in that it won't absorb sweat and turn into a solid funk with prolonged wear (foam latex is super-guilty of this evil). It's bad in that it's an excellent thermal insulator, and it doesn't absorb sweat. So, it just pools there making it feel icky. You want to integrate a removable cotton padding in the design. I expect it could just hold with a friction fit.

If I understand correctly, the technique Nostrum is describing is basically a half-lap joint. If I was doing such a project, I would most likely go with something like this. Here's my feeble attempt at describing it via ascii art

the Ms on the left side lock in place with the Ws on the right side. It doesn't have to be embedded magnets either. It can be hook-and-eye, Velcro, embedded snaps, embedded 3M command-release tabs (one use only). All with varying ability to hide the visibility of the steam. If you wanted to get really fancy, you could use small partial sliding dovetails...but don't worry about that.

Another option (which I like less and less the more I think about it) could potentially be to make bracers in medium weight tooling leather. If you make a long and very careful skive-joint bonded with contact cement, the seam line is very close to invisible. Then, to put it on or take it off, you soak the thing (or your arm) in lukewarm water. Properly designed, this could let it stretch just enough to slide on and off. But yeah, there are safety issues. If you make the thing too tight, it could give you circulation problems, particularly if anything happens that results in swelling (one of which is circulation problems, creating an icky cycle). So with this technique, I'd either need to make the thing incredibly loose, or keep a pair of EMT scissors on hand so I could cut it off quickly and safely in an emergency...soo, yeah, probably wanna ignore this idea.

Hmm, I get what you mean about the half-lap joint. If I make the gauntlet a little thicker than I was originally planning, that could work. I could also probably make a slip-on one because there are gloves underneath. I'll have to play around and see what works. Thanks!

Shit. Sorry, I totally forgot to go looking for the armour piece. I'll do it when we get back from the park.

What I was describing is basically what Verdatum has described, but because we work with vacuformed plastic, we don't have extra thickness to play with, and so glue on an extension strip of styrene to one side, which has rare earth magnets in it, and attach rare earth magnets to the underside of the other side of the opening. We seat the magnets into the plastic on the W side.
The only reason we use magnets over velcro is the thickness of it.